$S$	Entropy generation, J kg−1 K−1
$Q$	Heat, J
$T$	Temperature, K
$E_{\mathrm{in}}$	Input energy, J
$\dot{w}$	Heat dissipated at a certain temperature, J/s
$W$	Light output energy, J
$E_{irr}$	Irreversible energy, J
$P$	Power
$t$	Time, s
$U$	Voltage drop, V
$I$	Electric current, A
$\lambda$	Wavelength, nm
$R$	Resistance
$S_e$	External entropy generation
$S_i$	Internal entropy generation
$Q_e$	Heat dissipated into the environment, J
$K_{\lim }$	Limit constant
$C_p$	Capacitance of pyroelectric material
$\eta$	Absorption coefficient of radiation
$A$	Electrode area, m2
$T_f$	Final temperature, K
$T_i$	Initial temperatures, K
$\psi$	Exergy
$G$	Specific enthalpy, J/kg
$R$	Thermal resistance
$\mathrm{a}$	Ambient
$\mathrm{c}$	Case
$\mathrm{CS}$	Case-to-sink
$\mathrm{FoM}$	Related to the figure of merit
$in$	Input
$j$	Junction
${\eta }_{\coprod }$	Second law coefficient
$Z_{power}$	Uniformity coefficient
$T\left(\mathrm{X}\right)$	Temperature-dependent distance, K
$N_f$	Total number of cycles to failure
$F$	Driving force, N
P	Pressure
$T\left(t\right)$	Temperature-dependent time, K
$J_p$	Heat flux through the boundary
$W\left(t\right)$	Work by deformation
$V$	Solder volume
$kT$	Thermal energy
$D$	Diffusivity
$N$	Avogadro’s number
$M$	Mass rate
$\overrightarrow{q}$	Heat flux
$gradT$	Temperature gradient
$t_f$	Failure time
$C$	Heat capacity
$h$	Convective heat transfer coefficient
$D_N$	Damage parameter
$Q_{cyc}$	Unit cycle energy, J
$k$	Wear coefficient
$H_{ar}$	Hardness pressure
$L$	Normal load
$B$	(dw/ds) for a particular process
jc	Junction-to-case
ja	Junction-to-ambient
$p$	Related to processor
$out$	Outlet
$S$	Sink
$sa$	Sink-to-ambient